Gasification burner

ABSTRACT

A gasification burner for combustion of a fuel, comprises a barrel having a front and a back, wherein exhaust gas produced by combustion exits at an outlet, a first air inlet into the barrel and a fuel inlet into the barrel, each positioned adjacent the back, wherein air at a first flow rate and fuel at a fuel flow rate are deliverable at the first air inlet and the fuel inlet, respectively, and a secondary air link operatively connected a second air inlet. The second air inlet is positioned closer to the front of the barrel than the first air inlet, and air at a second flow rate is deliverable at the second air inlet from the secondary air link and into the combustion chamber. A slag trap is operatively connected to the barrel so as to be able to receive slag generated from combustion of the fuel in the barrel, and the slag trap is closer to the back than the second air inlet. The second air inlet is offset with respect to the front from the secondary air link.

FIELD OF THE INVENTION

This invention relates to burner technology, and more particularly to a gasification burner.

BACKGROUND OF THE INVENTION

Cyclone burners or furnaces were first developed back in the 1940s by Babcock and Wilcox. Generally, such furnaces are designed to burn coal as a fuel. The coal used is ordinarily a high rank coal with low water content. The coal and air are introduced at a back of a cyclone barrel and ignited. The air and fuel mixture can be introduced tangentially, or axially. Typically a secondary air source is also introduced all along the barrel to help increase combustion. Air swirls in a circular pattern around a primary axis of the barrel, enhancing combustion. Such known cyclone furnaces operate at relatively high temperatures (in excess of 1600° C.).

Not all of coal is comprised of hydrocarbons. Coal also contains materials which are non-combustible at the temperatures of operation of such cyclone furnaces. Typically such materials are referred to as ash or slag and include metal oxides, silicon or calcium oxides and various metals. Depending on the type of fuel burned these non-combustible materials may form slag or fly-ash or both. Slag is generally liquid at the temperatures associated with combustion of coal, and steps must be taken to collect and remove slag from the burner. Fly ash comprises the fine particles that rise with the flue/exhaust gases. Fly ash may include not only non-combustible components of the fuel, but may also include larger combustible particles which did not reside in the cyclone burner for sufficient time to be completely burned. Although fly ash can be collected by electrostatic precipitators, in instances where the exhaust gases are intended to be used as a heat source, fly ash may be undesirable. This is because as the fly ash is carried along with the exhaust gas and reaches a main boiler or any other heat transfer surface, the hot fly ash will tend to deposit on any cooler surface. As a result, efficiency of any heat transfer process will be reduced until the deposited fly ash is removed.

The Babcock and Wilcox furnace uses coal that produces a sticky fly ash upon combustion. Further, the sticky nature of the fly ash causes it to adhere to the walls of the interior. This provides a sticky surface onto which the coal particles also attach to the inner wall. Superheated air then passes over the stationary coal particles, allowing combustion to take place. This type of construction is relatively expensive, as water lines are provided to cool the walls and steps have to be taken to remove the accumulating fly ash.

The type of fuel used matters in the creation of slag and fly-ash. If the fuel is coal with an ash fusion temperature at a certain temperature, and the cyclone burner is run at a temperature above that ash fusion temperature, ash from the coal tends to become slag during combustion. If the burner is run at a temperature below the ash fusion temperature, ash from the coal tends to form fly-ash. It would therefore be desirable to provide a burner of improved construction with enhanced ability to burn fuel towards complete combustion (i.e., a gasification burner) without need to adhere particles to the wall of the burner, as well as to provide a burner which controls amounts of fly ash and slag produced.

SUMMARY OF THE INVENTION

In accordance with a first aspect, a gasification burner for combustion of a fuel, comprises a barrel having a front and a back, wherein hot exhaust gas produced by combustion exits at an outlet, a first air inlet into the barrel and a fuel inlet into the barrel, each positioned adjacent the back, wherein air at a first flow rate and fuel at a fuel flow rate are deliverable at the first air inlet and the fuel inlet, respectively, and a secondary air link operatively connected to a second air inlet. The second air inlet is positioned closer to the front of the barrel than the first air inlet, and air at a second flow rate is deliverable at the second air inlet from the secondary air link and into the combustion chamber. A slag trap is operatively connected to the barrel so as to be able to receive slag generated from combustion of the fuel in the barrel, and the slag trap is closer to the back than the second air inlet. The second air inlet is offset with respect to the front from the secondary air link.

From the foregoing disclosure and the following more detailed description of various embodiments it will be apparent to those skilled in the art that the present invention provides a significant advance in the technology of cyclone burners. Particularly significant in this regard is the potential the invention affords for providing a burner which enhances combustion of fuel, and enhances slag removal. Additional features and advantages of various embodiments will be better understood in view of the detailed description provided below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a gasification burner in accordance with one embodiment.

FIG. 2 is a front view of the gasification burner of FIG. 1.

FIG. 3 is a back view of the gasification burner of FIG. 1.

FIG. 4 is a top view of the gasification burner of FIG. 1.

FIG. 5 is a cross section view of the gasification burner taken along line 5-5 in FIG. 4, showing the secondary air inlet and its position with respect to the front of the barrel and a slag trap.

FIG. 6 is a cross section view of the gasification burner taken along line 6-6 in FIG. 4, showing the slag trap.

FIG. 7 is a schematic view of air flow within the burner in accordance with one embodiment, showing how a secondary air source biases larger particles toward the back, while largely combusted exhaust air moves towards the front.

FIG. 8 is an isometric view of another embodiment of a gasification burner wherein the travel path extends from the back to the front past the slag trap.

FIG. 9 is a side view of the embodiment of FIG. 8.

FIG. 10 is a back side view of the embodiment of FIG. 8.

FIG. 11 is a cross section view of the embodiment of FIG. 8, showing layers of the barrel and jacket in accordance with one embodiment.

FIG. 12 is a schematic view of a use of a gasification burner in a drying device for reducing a volume of organic material such as garbage.

FIG. 13 is a schematic view of a use of a gasification burner as a source of heat for a turbine to generate electricity.

FIG. 14 is an isometric schematic view of another embodiment of a gasification burner with vertical alignment such that the front is adjacent a top and the back is at a bottom.

FIG. 15 is a partially exploded isometric view of the embodiment of the gasification burner of FIG. 14.

FIG. 16 is a side view of the embodiment of the gasification burner of FIG. 14.

FIG. 17 is another side view of the embodiment of the gasification burner of FIG. 14.

FIG. 18 is another embodiment of a gasification burner using a horizontal burner and a vertical burner together.

It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the gasification burner as disclosed here, including, for example, the specific dimensions of the air inlets will be determined in part by the particular intended application and use environment. Certain features of the illustrated embodiments have been enlarged or distorted relative to others to help provide clear understanding. In particular, thin features may be thickened, for example, for clarity of illustration. All references to direction and position, unless otherwise indicated, refer to the orientation illustrated in the drawings.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

It will be apparent to those skilled in the art, that is, to those who have knowledge or experience in this area of technology, that many uses and design variations are possible for the burner disclosed here. The following detailed discussion of various alternate features and embodiments will illustrate the general principles of the invention with reference to a gasification burner suitable for use as a heat source. Other embodiments suitable for other applications will be apparent to those skilled in the art given the benefit of this disclosure.

Turning now to the drawings, FIG. 1 shows an isometric view of a gasification burner 10 in accordance with one embodiment. The burner can burn fuels such as low rank coal with relatively high water content, for example, 25%. The temperature of operation is typically cooler than other known burners, on the order of 1175° C. to 1600° C., depending on the type of coal burned. The burner 10 has a barrel 12 which defines a primary axis 14 extending along a length of the barrel from a front 15 to a back 13. As shown, the barrel is primarily cylindrical in shape. A slag trap 20 extends outside a circumference of the generally cylindrical barrel. Products of combustion of the fuel which are liquid are advantageously collected at the slag trap. First air connector or link 30 and fuel inlet 40 provide a supply of air and fuel into an interior of the barrel. Optionally the first air link 30 and the fuel inlet 40 merge at a first air inlet 44 (best seen in FIG. 2) at the barrel so that the air and fuel enter into the barrel 12 of the burner 10 together. The fuel air mixture is ignited using ignition inlet 90 (which can be, for example, a fuel oil to help start the process, either at the first air inlet 44 or remote from the inlet) and combustion occurs inside the barrel. A secondary air link 60 allows secondary air to travel along the barrel through travel path 77 and be preheated by residual heat from combustion in the barrel until the air enters the barrel at a second air inlet 50. Extending from the barrel at or adjacent the front 15 of the burner is a snout 25 having an outlet 55. The snout 25 can have an inner diameter 32, as shown. Exhaust air from combustion is routed to the snout and out the outlet 55. During combustion of the fuel, a flame is generated. Depending on fuel and air flow rate at the inlets, the flame may be contained within the burner or throw an incandescent flame up to 7 metres. For certain applications, partially combusted larger particles of coal fuel may be ejected from the snout 25.

Optionally a controller 80 may be provided. The controller may be operatively connected to an ignition port or inlet 90, the first air inlet 44, the fuel inlet 40 and the second air inlet 50 so as regulate the combustion process. Primary air at the first air inlet can have a first flow rate, fuel at the fuel inlet 40 can have a fuel flow rate, and secondary air at the second air inlet can have a second flow rate. The controller can control each of these rates, either together or in isolation, and can be configured to maintain a pressure gradient between the first flow rate and the second flow rate such that air from the second inlet flows toward the first air inlet. The controller may also be configured to regulate the air flow rates and fuel flow rate such that a maximum temperature of combustion in the barrel occurs between the first air inlet and the second air inlet, most preferably generally adjacent the slag trap 20. Alternatively, the controller may be configured such that the first flow rate, second flow rate and fuel flow rate result in larger, incompletely combusted particles of fuel exiting the snout at the front of the barrel. Sensors (not shown) may be positioned at various locations on and in the burner to monitor combustion and provide feedback to the controller. The controller 80 may also include one or more display screens presenting information about the combustion process, such as, for example, combustion temperatures, so an operator can manually adjust or control flow rates, ignition, etc.

FIG. 2 shows a view of the burner 10 from the front looking into the snout 25 and toward the back. Air at a first flow rate and fuel at a fuel flow rate enter at first air inlet 44. Significantly, in designs where complete or nearly complete gasification is desired, i.e., where non-combustible portions of the coal form slag, the coal introduced may be screened to particle sizes of less than 20 Mesh (less than about 0.85 mm), and more preferably about 20-100 Mesh (about 0.85 mm-0.15 mm). Also, coals with low ash content, relatively low water and low moisture content are desirable as a source of fuel. The coal and air inlets are optionally merged together and can be introduced into the barrel, for example, in a direction tangential to a primary axis. As shown in FIG. 2, the inlets introduce air and fuel so as to generate a rotating or cyclonic motion within the barrel. Alternatively the first air inlet and fuel inlet may be positioned on the back instead of on the circumference of the barrel. A jacket 70 surrounds at least a portion of the circumference barrel 12, and defines a travel path 77 for secondary air from the secondary air link 60 along the barrel. During combustion, the barrel warms, and some of the heat is transferred to the secondary air. An exterior 75 of the jacket 70 forms the outermost circumferential layer of the burner 10. The slag trap 20 is shown to extend beyond and below the circumference of the generally cylindrical barrel. The slag trap 20 may have components 43 for crushing slag, and an auger 21 for routing the slag away from the burner. This would be particularly desirable for high volume operations to help prevent slag from accumulating. FIG. 3 is a view from the back 13 and also shows an access port 67. Access port 67 may be formed as a hinged door, for example to help with inspection of the combustion process. Optionally the igniter for initial combustion of the fuel may be positioned in the access port, and a glass hole 66 may be provided for inspection.

FIG. 4 is a top view of the burner 10 showing the combustion chamber 17 formed in an interior of the barrel 12. The primary axis 14 extends from front 15 to back 13 along the generally cylindrical shaped burner. First air inlet 44, fuel inlet 40 and ignition port 90 are shown generally adjacent the back 13, and closer to the back than the slag trap 20. First air inlet 44 and fuel inlet 40 are combined so that primary air and fuel enter the combustion chamber together. As shown, the second air link 60 and second air inlet 50 are positioned generally adjacent the front. The slag trap is connected to the combustion chamber 17 by a slag trap opening 65. The slag trap is positioned closer to the front than the first air inlet 44 and closer to the back than the second air inlet 50 (with respect to the primary axis). Thus, the slag trap is positioned between the first air inlet and the second air inlet with respect to the primary axis. This arrangement is advantageous for controlling combustion of the fuel, as described in greater detail below.

FIG. 5 is a side view taken along line 5-5 in FIG. 4 which is along the primary axis 14. Air from the secondary air link 60 is not introduced into the combustion chamber directly. Rather, secondary air is preheated by traveling within jacket 70 along travel path 77, until reaching second air inlet 50. As shown in the Figs., the jacket can extend around a part of the barrel; here, at least one revolution around the barrel is made between secondary air link 60 and second air inlet 50 into combustion chamber 17. FIG. 5 shows a secondary axis 16 of the burner perpendicular to the primary axis 14 direction between the front 15 and back 13. Secondary air can be introduced to the barrel in a direction tangential to the primary axis. Alternatively, the second air inlet may be aligned at an acute angle with respect to the secondary axis towards the back. The acute angle may be 4-10 degrees, for example. The barrel 12 has a combustion chamber diameter 22, and the snout has an outlet diameter 32. Preferably the outlet diameter 32 is less than the combustion chamber diameter 22. This advantageously allows exhaust gases to exit near the center while larger particles are spun by the cyclone effect toward the outside of the barrel.

FIG. 6 is a cross section view taken along line 6-6 in FIG. 4 which shows the slag trap opening 65 operating connecting an interior or combustion chamber 17 of the barrel 12 with the slag trap 20. The slag trap opening 65 extends past the outer circumference of the barrel to connect to the slag trap 20. Components 43 may be provided to crush received slag, ash or a mixture of both, and an auger 21 can be provided to route such materials away from the burner 10.

FIG. 7 is a schematic view of air flow in the burner in accordance with an embodiment where flow of larger coal particles is inhibited by the secondary air. Air flow from the first air inlet initially travels circumferentially near the back as shown by the left side arrow. Coal particles combust, typically forming a large percentage of gaseous volatile matter and a heavier carbon char. Since the air is spinning, the lighter, gaseous volatile matter migrates toward the center of the barrel while the heavier char remains closer to the outer circumference of the barrel until oxidized to a gaseous material such as carbon monoxide allowing for migration to the center of the barrel. Fully combusted hot exhaust gases, including water vapour and carbon dioxide, exit through the center along the primary axis.

At the back of the burner, where the heavier particles tend congregate, there is a relatively low amount of oxygen. Preheated secondary air enters at or near the front of the burner, preferably in a circumferential direction essentially the same as the primary air. Advantageously, the secondary air is denser than air in the burner, including the exhaust gases. This difference in density can be due to the fact that the secondary air is cooler than the primary air. Thus, the heavier secondary air is flung toward the outer circumference of the barrel, as shown by the right side arrow in FIG. 7. The secondary air migrates towards the back of the burner and thereby partially contains the mixture of primary air and partially combusted fuel/char. As the secondary air heats up, it becomes lighter and moves toward the vortex of partly combusted fuel/char, providing a source of oxygen to enhance combustion. The inlet rates can be adjusted to take into account the type of fuel used such that maximum temperatures of combustion and pressures occur generally adjacent the slag trap. Gasification burners as disclosed herein may be referred to as entrained fuel cyclone burners since the coal is swept along controlled flows of air and exhaust gases.

Gasification burners as disclosed herein may also be used to burn high ash fusion temperature coals as part of a pulverized coal fired boiler. With certain types of coal it may be desirable to have some of the larger combustible particles of the coal fuel with low volatile matter exit the snout without completely combusting. Such larger particles are devolatilised and can be used for applications requiring low volatile matter, high fixed carbon content coal. Further, the hot exhaust air may be used as a source of heat for other operations, such as drying and setting low rank coals. In that environment, generally it is desirable to have as little fly ash as possible. The gasification burners disclosed here advantageously accomplish this, while also allowing for the option of use in production of low volatile matter, high fixed carbon content coal for use in applications requiring such coal.

FIGS. 8-11 show several views of another embodiment of a gasification burner 210, where the primary or first air access link 230 is combined with the fuel inlet and introduced to the combustion chamber/interior 117 defined by the barrel at first air inlet 234, formed on an interior of the barrel 212. The fuel may also be ignited at or just prior to entrance into the combustion chamber 117. Optionally a combustion chamber access port 267 and glass hole 266 may be provided near the back 13, and the snout 25 at the front can be similar or the same to the snout in the earlier embodiment. The slag trap can be positioned about 45-85%, more preferably 50-75% of the length of the barrel from the back. The slag trap 20 is shown in FIG. 9 positioned in this embodiment about 50% percent of the length of the barrel 212 from the back, for example. Thus, from left to right (back to front) as shown in FIG. 9, there is the primary air link/first air inlet and the secondary air link, then the slag trap, then the second air inlet and finally the snout.

In accordance with a highly advantageous feature, the secondary air link 260 is moved from generally close to the front 15 and to the second air inlet 250 into the combustion chamber to generally close to the back 13. That is, the secondary air port is closer to the back than the slag trap 20. Both the first air inlet 234 and the second air inlet 250 are positioned on a circumference of the barrel 212. The second air inlet 250 can be formed as an opening in the innermost layer 256 operatively connected to the air travel path 177. The secondary air source is designed to slow and control combustion of fuel as in the first embodiment, and may be introduced to the combustion chamber 117 at the second air inlet 250, which is in a position similar to the second air inlet 50 of the first embodiment.

For spacing considerations the primary air link 230 (shown in FIGS. 8 and 9) may be positioned on the barrel opposite the secondary air link 260. The air travel path 177 (shown in FIG. 11) is positioned between the jacket or outermost layer and the innermost layer of the barrel. The air travel path is modified from the first embodiment to account for the relative change in position between the secondary air link 260 and the second air inlet 250. Elongation of the air travel path along most (i.e., at least 50%, more preferably at least 80 or 90%) of a length 42 of the barrel allows for additional heating of the air prior to introduction into the combustion chamber. This gives the secondary air a longer dwell time in the air travel path, and so further heats the secondary air to a temperature closer to the temperatures inside the combustion chamber. The air travel path can be any path inside the burner from secondary air link 260 to the second air inlet 250, including a straight channel, a serpentine path or a path which makes at least one revolution around the central axis 14. All of the primary or first air can be introduced into the combustion chamber closer to the back (i.e., at inlet 234) than the slag trap (as considered along the primary axis 14). All of the secondary air can be introduced into the barrel (via link 260) closer to the back than the slag trap, and all of the secondary air can be introduced into the combustion chamber closer (i.e., at inlet 250) to the front than the slag trap.

FIG. 10 shows the relative location of the primary or first air link 230 with respect to the secondary air link 260. Both primary air and secondary air may be introduced to the barrel in the same direction, such as clockwise when viewed from back to front. It will be readily apparent to those skilled in the art given the benefit of this disclosure that the relative positions can be reversed and/or the air flow can be counterclockwise. Secondary air at a second flow rate behaves in much the same manner as in the previous embodiment, and can be controlled to allow largely combusted fuel (gas) to flow out the outlet while blowing larger particles back, effectively increasing the amount of time spent by such particles in the combustion chamber and thereby increasing the amount of combustion of the fuel.

A series of layers of materials may be used in the circumference of the barrel in accordance with this embodiment. The series of layers is useful to provide transition between the hot, abrasive combustion chamber and the ambient environment. An innermost layer 256 shown in FIG. 11 is preferably strong enough to withstand the high heat and abrasive conditions of the combustion chamber, while the outermost layer or jacket 288 is cool enough to avoid high heat on the exterior of the gasification burner which could cause scalding or burning if touched. Since temperatures can exceed 1400° C. in the combustion chamber the innermost layer needs to be able to withstand such high heat. Innermost layer 256 can comprise a first ceramic material such as a firebrick, insulating castable or other similar high temperature stable material. Alternatively, a high strength, high temperature alloy metal such as SS317 or 253MA for example, may be used as the innermost layer. When the innermost layer is a firebrick or nonmetal material, an additional layer of a ceramic paper 269 may be used to help connect the firebricks together. When the innermost layer is a metal alloy, optionally a layer of a thermal barrier coating can be applied for further insulation and corrosion resistance.

The air travel path 177 operatively connects the secondary air link 260 to the second air inlet 250 between the innermost layer 256 and the jacket 288. In the embodiment of FIG. 11 the air travel path is positioned between the additional structural layer 277 and a second structural layer 278. Both of these structural layers 277, 278 can comprise relatively thin layers of steel, for example. Optionally an insulating layer 279 such as a ceramic blanket may be positioned between the jacket 288 and the second structural layer 278. The outermost layer 288 can comprise, for example, an alloy steel such as a zinc/aluminium alloy-coated steel such as ZincAlume® comprising 55% aluminium, 43.5% zinc and 1.5% silicon.

The ceramic paper and ceramic blanket can comprise alumino-silicate ceramic fiber based non-woven fabric materials. Typical properties are: 47% Al₂O₃; total Al₂O₃ and SiO₂>97%; total Fe₂O₃: <1.0%; density: 10 lb/ft³; tensile strength: 25 PSI; loss of ignition (LOI): <9%; working temperature: 1,800° F. for continuous use; and 2300° F. maximum. Other combinations of heat resistant and insulating materials which define the air travel path and are suitable for use in gasification burners will be readily apparent to those skilled in the art given the benefit of this disclosure.

As higher temperatures may be experienced at the access port 267, slag trap 20 and snout 25, a second innermost layer 286 with the ability to withstand such higher temperatures may optionally be provided. In the embodiment of FIG. 11, the second innermost layer 286 is a ceramic material which may be positioned on a front surface of the back wall and a back surface of the front wall and at the slag trap.

The ceramic material may be extended to other locations as required. The ceramic material of the second innermost layer 286 may be the same or different than the innermost layer 256. Both innermost layers 256, 286 are positioned at the interior of the barrel and cooperate to define most of the combustion chamber. The material selected for use in the innermost layers depends upon the temperature inside the barrel and the chemical nature of the organic material used.

The output of the gasification burner is a function of the first air flow rate, the second air flow rate, and the fuel flow rate, as well as the ash fusion temperature of the fuel used. If the temperature inside the combustion chamber is higher than the ash fusion temperature of the coal, then little fly ash exits the snout. On the other hand, if the temperature inside the combustion chamber is lower than the ash fusion temperature of the coal, then fly ash will be formed which exits the outlet 55 of the gasification burner. In accordance with a highly advantageous feature, a controller of the gasification burners disclosed herein can control the settings of any or all of the first air flow rate, second air flow rate, and fuel flow rate, so that the output can be adjusted to produce either result.

FIG. 12 shows the use of one or more gasification burners for drying organic materials such as garbage. Garbage can come in many forms, may require sorting and may require a shredder 315 prior to drying. When drying or combusting garbage, heating can be direct or indirect. Also, drying/combustion may be split into several stages. This is particularly useful as combustion may be difficult when garbage is wet. That is, several stages may be required to achieve temperature sufficiently high to ensure complete combustion.

In the embodiment shown in FIG. 12, shredded garbage is introduced to a drying device such as dryer 310. The outlets from a gasification burner 210 (or multiple gasification burners, as required) are operatively connected to the dryer 310 to at least partially dry the garbage. One or more fireboxes 325 may be provided. Each firebox is a combustion device which compliments and supplements the drying device. Here, dried garbage is introduced to the firebox for complete burning. Unburnt coal may be combusted along with the dried garbage (either dried organic waste, dried plastics, or both) in the fireboxes. Flue/exhaust gases from the gasification burners may be directed to the fireboxes to adjust temperatures to ensure combustion, as needed. Upon essentially complete combustion of the organic materials, a screen 335 may be provided to separate metallic waste from resulting ash. Waste heat from the fireboxes may be routed to a waste heat capture device such as a turbine or microturbine 380. The drying/combustion devices advantageously incorporate the gasification burners into a design which significantly reduced the total volume of garbage.

FIG. 13 shows another embodiment where a heat generation device such as, for example, one of the gasification burners disclosed elsewhere in this application generate heat, and the heat is used by a turbine or microturbine 380 to generate electricity. When the heat generation device is one of the gasification burners disclosed herein, exhaust gas from the outlet of the gasification burner is operatively connected to the turbine or microturbine 380. The combustion of fuel may occur remote or separated from a heat transfer stage. For example, a vertical burner as described elsewhere in this specification can be used as a heat generation device, and the vertical burner is in turn operatively connected to a boiler used as a source of steam or superheated steam to drive the turbine and generate electricity. Such an arrangement can be particularly useful in situations where connection to an electric power grid is not convenient, such as a remote coal mine, for example. The heat generated by the gasification burner 210 can be delivered to the turbine in one of several ways. The turbine may use exhaust gas from an outlet of the gasification burner either directly, or indirectly by use of a heat exchange medium such as water or air. Also, the exhaust gas from the outlet at the front may do useful work (i.e., transferring heat) on least one of a drying device, an organic material upgrading device and/or a combustion device prior to or after arriving at the turbine. Further, in addition to other heat generation devices, a single gasification burner may be used, either vertical or horizontal, or multiple gasification burners may be used.

In the embodiment of FIG. 13 a pair of gasification burners 210, 410 are used, and the heat source for the turbine is supplied indirectly by using heated ambient air. Ambient air is introduced to the second gasification burner 410 at inlet 350 and is routed through the second gasification burner via a heat transfer device 450. The first gasification burner may be positioned horizontally with respect to the ground, while the second gasification burner 410 may be attached to the outlet of the first gasification burner and positioned vertically with respect to the ground. The second gasification burner may be used to help ensure more complete combustion of the fuel, such that nearly all solid material is collected at slag traps, and the exhaust gas has a very low amount of particulate matter. The heat transfer device can be piping which physically isolates the ambient air from the exhaust air, but allows for heat transfer between the two mediums. The exhaust air can be routed from outlet of the first gasification burner to the second gasification burner to a device such as a coal upgrading device 360 which uses some of the heat of the exhaust gas. From there, the somewhat cooler exhaust gas may be routed to a flue 290. The heated ambient air can be routed to the turbine 380 to provide a source of heat such that the turbine can generate electricity 390. Thus, the turbine can be designed to work with heated air, superheated steam or other suitable heat exchange medium. The electricity can advantageously be used to provide power to electrical devices associated with the gasification burner and any drying/combustion or upgrading devices, as well as other additional and unrelated components which use electricity. Optionally the heated ambient air can be routed from the turbine to the device 360 via link 370. Optionally a portion of the heated ambient air may also be routed directly to the device 360.

FIGS. 14-17 show another embodiment of a gasification burner. Here, gasification burner 510 is generally vertically aligned (with respect to the floor and gravity) such that the front 15 is at a top and the back 13 is at a bottom. In this embodiment gravity cooperates with the secondary air to help keep fly ash in the combustion chamber 517, and thereby help increase combustion. The slag trap 520 is moved to the back/bottom of the barrel 512, and is offset from the ground by a stand 599. Primary or first air link 530 and secondary air link 560 are positioned near the back/bottom. Air and fuel are introduced in a cyclonic manner similar to the embodiment of FIGS. 9-11, with a single fuel/air link 530 for primary air connecting to a single first air inlet 534 (shown in FIGS. 16 and 17) and the secondary air link 560 positioned adjacent the back/bottom of the burner 510, in the sense that both links 530, 560 are positioned below secondary air inlet 550 as shown in FIGS. 14, 16 and 17. No fuel is introduced at the second air inlet.

The secondary air link is brings air from outside of the barrel to the second air inlet 550 which connects to the combustion chamber. The secondary air link is operatively connected to the second air inlet 550 via an air travel path 577 (shown in FIG. 17) so that the second air inlet is offset from the secondary air link with respect to the front of the barrel. Second air does not merely enter the combustion chamber straight from the secondary air link. Rather, as with the other embodiments, the air is preheated by traveling along the elongate air travel path 577. Generally, the air travel path is at least 50% of the length 142 of the barrel. In the embodiments shown in the drawings, the air travel path is at least 80% or at least 90% of the length of the barrel. Insulating layers may be positioned along the walls of the barrel in a manner similar to the embodiment of FIGS. 9-11.

Positioned within the combustion chamber 517 of this embodiment is an insert 524. The insert may be positioned adjacent or above the second air inlet, and generally near the front/top. As shown in FIG. 15, the insert is positioned between the combustion chamber and the tube 526. The insert may be disc shaped, defining an opening operatively connecting the combustion chamber to the outlet. Alternatively, the insert may have a frustoconical shape. The opening has a diameter which is less than the diameter of the combustion chamber. This restriction acts to limit larger particles (which, due the cyclonic air flow, tend to congregate away from the primary axis of the barrel) from rapidly exiting the combustion chamber, and thereby aids in more complete combustion of the fuel.

Additional measures may be taken to ensure that the amount of fly ash exiting the burner is reduced. A tube 526 may be positioned on the side of the insert 524 opposite the combustion chamber, at the front/top. The opening of the insert is operatively connected to the tube 526, which in turn is operatively connected to a snout 525. Instead of having the outlet positioned on the top and coaxial with the primary axis, in this embodiment the outlet is at the snout 525 which is positioned on a circumference of the barrel adjacent the front 15. By adjacent the front it is understood to mean that the outlet is closer to the front than the second air inlet, as shown in FIGS. 16-17, for example. The snout 525 may contain a nozzle 535, which may be frusto-conical shaped, as shown, and defines a restrictive opening remote from the outlet smaller than the outlet of the snout 525. Having a restrictive opening with a smaller diameter the outlet diameter can help to ensure more complete combustion, especially of larger particles. The snout and nozzle also can cooperate to define an opening or openings for tertiary air inlet 591 from tertiary air link 590. Tertiary air can be introduced into the snout and nozzle in one of several ways, including at a single inlet, or a plurality of inlets arranged around the nozzle. The snout and nozzle may be integrally assembled. Alternatively the snout and nozzle may be formed as a unitary, or one piece construction.

The slag trap 520 is at the back when the outlet is at the circumference of the barrel. As shown in FIGS. 14-17, the back is at the bottom. During combustion of fuel, exhaust air has relatively laminar flow through the tube 526 until it contacts front cover 523. From there, the exhaust air would exit out the outlet, shown positioned at a right angle to the primary axis. In accordance with another highly advantageous feature of the invention, the tertiary air link 590 may be operatively connected to a tertiary air port 591 at the snout 525. The tertiary air link is adapted to introduce tertiary air into the snout. Preferably the air is introduced tangentially so as to generate a cyclonic air flow pattern. The result is a front of air around the outside which slows progress of any remaining uncombusted fuel particles, and helps with further combustion of such particles. Further, the tertiary air can serve to reduce the temperature of the air. For example, depending in part on the fuel used, exhaust air from combustion can be 1400° C. The tertiary air can be varied to reduce the exhaust gas exiting the outlet. This outlet exhaust gas temperature can be adjusted to work well as a heat source fro other devices, such as a turbine, an upgrading device or a drying device. For example, the outlet exhaust air of the snout may be reduced to about 900° C., and routed to a microturbine, and waste heat from the microturbine may be routed to a coal upgrading/pyrolyzing device, either with or without additional heat supplied directly from the gasification burner or an additional heat source. Optionally more than one tertiary air port may be provided.

FIG. 18 shows another embodiment of a gasification burner 610. Here a horizontally mounted gasification burner such as the burner of FIGS. 1-7 or FIGS. 8-11 can serve as a primary location for combustion of fuel. An exhaust channel 620 operatively connects the outlet of the gasification burner 210 to a second combustion chamber of a second gasification burner. Products of combustion at the first gasification burner 210 including hot exhaust gases, as well as some partial or incompletely combusted fuel, may enter the second combustion chamber for further combustion. In accordance with a highly advantageous element, the second gasification burner may be positioned vertically, that is, at right angles with respect to the gasification burner 210. Generally the second gasification burner may be similar to the vertical gasification burner of FIGS. 14-17. Instead of a fuel/air inlet, only air may be introduced at an air inlet 634. Optionally second air inlet 550 may be provided in a manner similar to the second air inlet in the vertical gasification burner of FIGS. 14-17. The combination of burners allows for more complete combustion of the fuel, reducing fly ash. Another embodiment of the invention comprises using a pair of vertical burners operatively connected together in a manner similar to the horizontal burner and vertical burner connection shown in FIG. 18. Any gasification burner or combination of gasification burners (vertical or horizontal) may be used in combination with other devices which can use the heat from the exhaust gases generated by such gasification burners.

From the foregoing disclosure and detailed description of certain embodiments, it will be apparent that various modifications, additions and other alternative embodiments are possible without departing from the true scope and spirit of the invention. The embodiments discussed were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to use the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled. 

What is claimed is:
 1. A gasification burner for combustion of a fuel, comprising, in combination: a barrel defining a combustion chamber and having a front and a back, wherein exhaust gas produced by combustion exits at an outlet; a first air inlet into the barrel and a fuel inlet into the barrel, each positioned adjacent the back, wherein air at a first flow rate and fuel at a fuel flow rate are deliverable at the first air inlet and the fuel inlet, respectively; a secondary air link operatively connected to a second air inlet, wherein the second air inlet is positioned closer to the front of the barrel than the first air inlet, and air at a second flow rate is deliverable at the second air inlet from the secondary air link and into the combustion chamber; a slag trap operatively connected to the barrel so as to be able to receive slag generated from combustion of the fuel in the barrel, wherein the slag trap is closer to the back than the second air inlet; and the second air inlet is offset with respect to the front from the secondary air link.
 2. The gasification burner of claim 1 further comprising a jacket surrounding a part of the barrel, wherein air travels along the jacket from the secondary air link to the second air inlet and into the combustion chamber defined by the barrel.
 3. The gasification burner of claim 2 wherein the secondary air link is positioned between the slag trap and the front of the barrel.
 4. The gasification burner of claim 1 wherein the barrel defines a primary axis extending from the front to the back.
 5. The gasification burner of claim 4 wherein the first air link is merged with the fuel inlet at the first air inlet into the barrel.
 6. The gasification burner of claim 5 wherein air and fuel are introduced to the barrel in a direction tangential to the primary axis.
 7. The gasification burner of claim 4 wherein air is directed into the barrel at the second air inlet in a direction tangential to the primary axis of the barrel.
 8. The gasification burner of claim 4 wherein the barrel has a secondary axis perpendicular to the primary axis, and the second air inlet is aligned at an acute angle with respect to the secondary axis such that air is directed into the barrel at the second air inlet towards the back.
 9. The gasification burner of claim 8 wherein the acute angle is 4-10 degrees.
 10. The gasification burner of claim 1 wherein the first flow rate, second flow rate and fuel flow rate can be varied to generate a maximum temperature of combustion in the barrel adjacent the slag trap.
 11. The gasification burner of claim 1 wherein the first flow rate, second flow rate and fuel flow rate can be varied to have incompletely combusted particles of fuel exit a snout at the front of the barrel.
 12. The gasification burner of claim 1 wherein the fuel is coal having a particle size of less than 20 Mesh.
 13. The gasification burner of claim 12 wherein the coal has a particle size of 100 Mesh to 20 Mesh.
 14. The gasification burner of claim 1 wherein the barrel has a barrel width, a snout extends from the barrel at the front, and the snout has an outlet width less than the barrel width.
 15. The gasification burner of claim 1 wherein the slag trap is closer to the front than the first air inlet.
 16. The gasification burner of claim 1 further comprising a controller which controls the first flow rate, second flow rate and fuel flow rate.
 17. The gasification burner of claim 16 wherein the controller is configured to regulate the air flow rates and fuel flow rate such that a maximum temperature of combustion in the barrel occurs between the first air inlet and the second air inlet.
 18. The gasification burner of claim 1 wherein the barrel has a length and the slag trap is positioned 45-85 percent of the length of the barrel from the back.
 19. The gasification burner of claim 2 wherein the barrel comprises an innermost layer and an air travel path operatively connects the secondary air link to the second air inlet between the innermost layer and the jacket.
 20. The gasification burner of claim 19 wherein the barrel further comprises an insulating layer positioned between the jacket and the air travel path.
 21. The gasification burner of claim 20 further comprising an additional layer attached to the innermost layer.
 22. The gasification burner of claim 20 wherein the jacket comprises an alloy steel, and the innermost layer comprises one of an insulating ceramic and a metal alloy coated with a thermal barrier coating.
 23. The gasification burner of claim 20 wherein the barrel further comprises a second innermost material, wherein each of the innermost layers cooperate to define the combustion chamber.
 24. The gasification burner of claim 1 wherein an outlet at the front is operatively connected to at least one of a drying device, an upgrading device, and a combustion device.
 25. The gasification burner of claim 1 wherein an outlet at the front is operatively connected to a turbine, and the turbine is adapted to generate electricity using heat from the exhaust gas.
 26. The gasification burner of claim 25 wherein the outlet is operatively connected to a heat transfer device, and the heat transfer device is adapted to transfer heat from the exhaust gas to ambient air to produce heated ambient air, and the turbine is adapted to receive the heated ambient air.
 27. The gasification burner of claim 25 wherein the outlet is operatively connected to a heat transfer device adapted to transfer heat from the exhaust gas to water from a boiler to produce steam, and the steam drives the turbine.
 28. The gasification burner of claim 25 further comprising a second gasification burner positioned between the outlet and the turbine.
 29. The gasification burner of claim 1 wherein the outlet is at one of the front and a circumference of the barrel adjacent the front.
 30. The gasification burner of claim 29 wherein the slag trap is at the back when the outlet is at the circumference of the barrel.
 31. The gasification burner of claim 1 wherein the second air inlet is positioned between the front and the secondary air link.
 32. The gasification burner of claim 2 wherein the secondary air link is connected to the second air inlet by an air travel path, the barrel has a length, and the air travel path is at least 50% of the length of the barrel.
 33. The gasification burner of claim 1 wherein the barrel has a combustion chamber diameter, the outlet is at a snout having an outlet diameter which is less than the combustion chamber diameter, and the snout is positioned outside the combustion chamber.
 34. The gasification burner of claim 33, further comprising a tertiary air link operatively connected to the snout at a tertiary air inlet and adapted to introduce tertiary air into the snout.
 35. The gasification burner of claim 1 further comprising an insert into the combustion chamber positioned adjacent the second air inlet, wherein the insert has an opening operatively connecting the combustion chamber to the outlet which has a diameter less than a diameter of the combustion chamber.
 36. The gasification burner of claim 1 further comprising: a second gasification burner having a second combustion chamber; and an exhaust channel operatively connecting the outlet of the gasification burner to the second combustion chamber of the second gasification burner.
 37. The gasification burner of claim 1 wherein the outlet is at a snout, and a nozzle is positioned in the snout which defines a restrictive opening remote from the outlet which is smaller than the outlet. 